1. Field of the Invention
The present invention relates to a brightness enhancement film having a reinforcing structure for use in a liquid crystal display. Particularly, the present invention relates to the brightness enhancement film including a light-refracting microstructure layer and a reinforcing layer at either side thereof. More particularly, the present invention relates to the brightness enhancement film having the reinforcing structure which has a degree of hardness greater than that of a substrate.
2. Description of the Related Art
Referring initially to FIG. 1, U.S. Pat. No. 5,626,800, entitled “Prevention of Groove Tip Deformation in Brightness Enhancement Film,” discloses a brightness enhancement film 1 including a substrate (i.e. base) 11 and a plurality of prism units 12 provided thereon. The prism units 12 are arranged and juxtaposed on a top surface of the substrate 11 in order. Each of the prism units 12 consists of a first inclined surface 12a and a second inclined surface 12b connected thereto, and serves to refract light penetrated through the substrate 11 in use for enhancing brightness of light.
In manufacture, the substrate 11 of the brightness enhancement film 1 has a bottom surface which is an ordinary flat surface and opposite to the top surface. However, the top surface and the bottom surface disposed on the substrate 11 of the brightness enhancement film 1 are unmatched in structure which may cause a specific degree of warpage of the brightness enhancement film 1 in nature. Furthermore, the brightness enhancement films 1 are piled upon each other on a conveyer (not shown in FIG. 1) if the products are finally made. This practice unavoidably causes warpage and abrasion of the surfaces of the brightness enhancement films 1, and disadvantageously affects quality and quantity of output of the brightness enhancement films 1.
U.S. Pat. No. 6,280,063, entitled “Brightness Enhancement Article,” also discloses another brightness enhancement film including a substrate, a prism unit layer and a light-diffusing surface. The prism unit layer and the light-diffusing surface serve as a top surface and a bottom surface of the substrate. This permits light to penetrate from the light-diffusing surface to the prism unit layer where light is emitted. The light-diffusing surface contains several light-diffusing particles which naturally diffuse light. Correspondingly, the prism unit layer is used to refract light penetrating the brightness enhancement film. Even though the brightness enhancement film has the light-diffusing surface at its bottom side, the light-diffusing surface cannot prevent warpage of the brightness enhancement film in nature. Furthermore, the light-diffusing particles of the brightness enhancement film protrude like raised particles on the light-diffusing surface and, thus, scrape the surface of another brightness enhancement film while piling upon each other. Also, this practice unavoidably causes warpage and abrasion of the surfaces of the brightness enhancement films, and disadvantageously affects quality and quantity of output of the brightness enhancement films.
The present invention intends to provide a brightness enhancement film having a reinforcing structure including a light-refracting microstructure layer and a reinforcing layer at either side thereof. The light-refracting microstructure layer is used to vary curvatures of a top surface, and the reinforcing layer is used to provide a specific degree of hardness in such a way to mitigate and overcome the above problem. Accordingly, the reinforcing layer can prevent warpage and abrasion of the brightness enhancement film.